This invention relates to a computer system containing a storage system where data used by a computer is stored, and more particularly, to a technology of controlling the state (encrypted/plaintext/mixed) of a storage area when the storage system has a function of encrypting data stored in a storage area and a function of decrypting data read out of a storage area.
The recent popularization of storage area networks (SANs) in which a storage system, a computer, and a management computer are coupled to one another by a dedicated line such as Fibre Channel is accelerating the increase in scale of computer systems. Also increasing is the public interest in secure data preservation and management as more information leaks from stolen recording disks or the like are reported. One of the methods to secure stored data is to give a storage system a storage area encrypting function for encrypting data read out of and written in a storage area (see JP 2007-28502 A and JP 2005-322201, for example).